Image to Base64
Encoder
Upload any image and get its Base64 string or Data URI instantly. Copy with one click, processed entirely in your browser.
Click or drag an image to upload
PNG, JPG, WebP, GIF, SVG
How It Works
Upload Image
Drop or select any image file (PNG, JPG, WebP, GIF, SVG).
Encode
Your image is converted to Base64 instantly in the browser.
Copy
Copy the Base64 string or full Data URI with one click.
Convert images to Base64 strings online to embed them directly in HTML, CSS, JSON, or email templates. ConverterUp's image to Base64 tool generates a clean encoded string or a full data URI ready to paste into a stylesheet, an SVG sprite, or a markdown document. It is useful for offline-first apps, transactional emails that must work without external requests, and inlining tiny icons to save HTTP requests. The encoding runs entirely in the browser, so confidential mockups and internal screenshots never leave your machine.
When inlining as Base64 actually makes sense
Inlining shines for assets under 4 KB where the cost of a separate HTTP request (DNS, TCP, TLS, request headers) outweighs the 33 % size penalty of Base64 encoding. Tiny icons in CSS pseudo-elements, single-pixel transparency PNGs, and small spinners are the canonical examples.
Transactional emails are the second clear win. Email clients block external image requests by default until the recipient clicks 'load images', so inlined logos and icons render immediately. Combined with the fact that emails are often archived for years, inlining guarantees the image still renders in 2030 even if your CDN is gone.
Offline-first PWAs and single-file HTML reports (downloadable invoices, exported dashboards, PDF-as-HTML) benefit from inlining for the same reason: the document is self-contained and works without network. Same goes for signed bundles shipped as a single file.
Where inlining fails: any image above ~10 KB, anything reused across pages (you lose HTTP caching), animations and video frames, and anything that needs lazy-loading. For those, keep a real file and reference it by URL — the browser's HTTP cache will outperform inlining within 2-3 page views.
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Performance tradeoffs you should know
Base64 encoding inflates binary data by exactly 33.3 %: every 3 input bytes become 4 output characters. A 9 KB PNG becomes a ~12 KB string. Gzip and brotli can claw some of that back (~10-15 % for typical image data) but you cannot recover the full overhead.
Cache loss is the bigger penalty for repeated assets. A 50 KB logo referenced as <img src="/logo.png"> is downloaded once and cached for every subsequent page view. The same logo inlined in 20 emails or 20 HTML pages is downloaded 20 times. For a single-page asset this does not matter; for shared assets it is a real bandwidth and parse-time cost.
CSS parse time grows non-linearly with stylesheet size on low-end devices. A stylesheet that grows from 50 KB to 200 KB because of inlined images can add tens of milliseconds to first paint on mid-range Android phones. Treat inlining as a budget, not a default.
Memory: the browser holds the decoded image data and the original Base64 string in memory until the document is parsed. For very large inlined assets this can briefly double memory use compared to a URL-referenced file.
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Data URI structure and where to paste it
The data URI format is data:<mime>;base64,<encoded>. Example: data:image/png;base64,iVBORw0KGgo…. The MIME type tells the consumer how to interpret the bytes — image/png, image/jpeg, image/svg+xml, image/webp, etc. Get the MIME wrong and the browser will refuse to render the image even if the bytes are correct.
In HTML: <img src="data:image/png;base64,…" alt="...">. In CSS: background-image: url("data:image/png;base64,…");. In JSON: store the full data URI as a string field, then assign it to the src at render time. In Markdown:  works in most renderers but check that yours doesn't truncate long strings.
For SVG, prefer inlining the SVG markup directly (cheaper and stylable with CSS) over encoding the SVG as Base64. If you must Base64-encode an SVG, use image/svg+xml as MIME and consider URL-encoding instead — it produces a smaller, more readable result than Base64 for text-based formats.
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Frequently asked questions
When should I inline an image as Base64?
Base64 makes sense for very small assets (under 4 KB) where a separate HTTP request would cost more than the size overhead. For larger images keep regular files because Base64 inflates size by about 33 %.
Is there a file size limit?
ConverterUp accepts images up to 25 MB. Encoded strings can become extremely long, so most editors and email clients struggle past a few megabytes.
What is the difference between a Base64 string and a data URI?
A Base64 string is just the encoded bytes, while a data URI prepends the MIME type, like data:image/png;base64,.... Use the full data URI in src or url() and the raw string when you provide the type elsewhere.
Which image formats are supported?
PNG, JPG/JPEG, WebP, AVIF, GIF, and SVG. The MIME type in the data URI is set automatically based on the file you upload.
Can I copy the result directly into JSON without escaping?
Base64 strings contain only <code>A-Z</code>, <code>a-z</code>, <code>0-9</code>, <code>+</code>, <code>/</code>, and <code>=</code> — all safe inside a JSON string. The full data URI is also JSON-safe. The only character you may need to escape is the JSON quote that wraps the value itself; ConverterUp's copy buttons already produce a JSON-ready string.
Should I use Base64 or URL encoding for SVG inlining?
Use <strong>URL encoding</strong> for SVG. SVG is text, so percent-encoding only the unsafe characters (<code>%, #, <, ></code>, quotes) produces a smaller and more readable result than Base64. Many SVG-to-data-URI tools default to URL encoding for that reason.
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